Oral care agents can be applied to teeth via varnish compositions that release the agents into the teeth. Such release takes place either via water present in the formulation, or as moisture from the teeth ingresses through the inner surface of the varnish. The use of varnish compositions as a carrier for oral care agents, brings about several advantages. Particularly, applying a liquid varnish composition onto the teeth can be done easily. This is, e.g., by painting or other spreading techniques such as by using a syringe, brush, or spatula.
A particular advantage is that dental trays, or other invasive application devices, can be avoided, as a varnish composition can be painted or otherwise be manually spread onto the teeth. This is of benefit in a professional care environment, but also allows patients or users to apply such oral care composition by themselves.
However, wetting of the outer surface of the varnish can cause the oral care agents to leak into the mouth (e.g., towards the lips) in addition to into the teeth, thereby reducing the amount of oral care agent delivered to the teeth. The varnish composition may also be soft and easily washed away, thereby not allowing an effective amount of the oral care agent to be delivered to the teeth. The deposited varnish composition may also have a rough surface that can irritate the lips and other soft tissues. Furthermore, the deposited composition may have an undesirable appearance in terms of a rough surface, poor colour, and/or undesirable reflectance properties.
The foregoing issues are recognized in the art. In US 2005/0249677 A1 reference is made to a bleaching method that involves painting a bleaching composition directly onto a person's teeth. It is thereby mentioned that a perceived advantage of paint-on bleaching is that it eliminates the need for a dental tray, but that the main disadvantage of a paint-on bleaching composition is that it remains directly exposed to the person's saliva and disruptive forces found in a person's mouth. In the reference, it is foreseen to apply a dental bleaching composition onto the teeth, applying a protective composition on or adjacent to gingival tissue, and placing a moisture-resistant barrier layer over the tooth surface to be bleached. The barrier layer is a shaped device, e.g., in the form of a dental tray, sheet, strip, or patch. Therewith, i.e., by providing a shaped device to be placed in the mouth, the reference largely reduces, if not altogether diminishes, the advantages associated with applying the oral care agent via a composition that can be painted onto the teeth.
Further, a dual layer whitening varnish is available under the trade name Philips Zoom QuickPro product. This is typically used in a short, five-minute dental office procedure. The product is based on a two-layer technology with a 20% hydrogen peroxide whitening varnish followed by a sealant layer that dries in seconds and locks the hydrogen peroxide layer into place. Whilst this product provides a considerable advancement in teeth whitening technology, it would be desired for some applications, e.g. to further facilitate domestic use, to provide a single layer varnish.
It is desired to provide a system and method are which can overcome some of the problems with systems as existing prior to the aforementioned QuickPro product, such as having a reduced leakage rate of an oral care agent into a mouth, but which is fully based on a varnish-type composition. I.e., a system is sought that is entirely based on compositions that can be easily applied onto tooth surfaces as a fluid, and which are thereafter cured.